1. Field of the Invention
The present invention relates to a gymnastic apparatus, and more particularly to an elliptical exercise machine satisfying human factors engineering.
2. Description of the Related Art
According to a design of a conventional elliptical exercise machine, as shown in FIG. 7, a vertical rod 92 is upwardly extended from a front end of a machine rack 91. Two swing arms 83 are respectively pivoted to two sides of the vertical rod 92. A driving wheel 94 is installed to a rear of the machine rack 91. Two sides of the driving wheel 94 are respectively provided with a crank 95. A stepping rod 96 is respectively disposed to two sides of the machine rack 91, and a pedal 97 is respectively fastened to the two stepping rods 96. Front ends of the two stepping rods 96 are pivotally connected to other ends of the two swing arms 93. Rear ends of the two stepping rods 96 are respectively connected to the two cranks 95. The front ends of the stepping rods 96 are towed by the swing arms 93 to perform a reciprocating motion along an arc orbit. The rear ends of the stepping rods 96 are towed by the cranks 95 to move along a circle orbit. Accordingly, the pedals 97 on the two stepping rods 96 can move along an elliptical exercise orbit.
However, the lengths of the cranks 95 need to be regulated to satisfy demands on step lengths and heights for users with different body heights if the conventional elliptical exercise machine must suit users with different body heights. The design of the conventional elliptical exercise machine is that pedals 97 are fastened on the stepping rods 96, and the two stepping rods 96 are directly connected to the swing arms 93 and the cranks 95. When the design of the step lengths and heights is increased, the angles of the pedals 97 are also increased during the exercise process. The comforts and joint forces of users are influenced and difficult to satisfy the human factors engineering.
Moreover, if the elliptical orbit motion performed by the conventional elliptical exercise machine reaches a left acme and a right acme of an elliptic orbit, the curvature variation will be the maximum. In another word, tangential velocity variation reaches the maximum. Consequently, when the two pedals 97 stepped by the user are operated to reach the left acme and the right acme of the elliptical orbit, the operation is not smooth to cause inertia.